Differential diagnosis between oral fibroma and inflammatory hyperplasia : a proposal for histopathological criteria

Abstract

Aim: The present study proposed histopathological criteria for the differential diagnosis between those pathological entities. Materials and methods: Histological sections of lesions histopathologically diagnosed as Oral Fibroma (n=61) and Inflammatory Hyperplasia (n=75) and were submitted to different techniques (Hematoxylin- Eosin; Masson Trichrome and Phosphomolybdic acid - Picrosirius red) to allow quantitative and qualitative analysis. The qualitative analysis of collagen density was based on sections stained by Hematoxylin- Eosin and focused in the center and periphery of each lesion. Results: Wound and collagen fibers were more frequent and higher in Oral Fibroma, while parallel fibers were more frequent in Inflammatory Hyperplasia (Fisher’s exact test, p<0.05). The percentage of parallel collagen fibers beneath the epithelium was 72.22% and 92.3% in Oral Fibroma and Inflammatory Hyperplasia, respectively (Mann Whitney U test, p<0.05). The parallel collagen fibers in the center of the lesion was found in 84.6% of Inflammatory Hyperplasia cases and was absent in 88.88% of Oral Fibroma. The central portion of Oral Fibroma had characteristically a dense and wound arrangement of collagen fibers. Conclusion: Oral Fibroma and Inflammatory Hyperplasia have distinctive features that may be useful in routine histopathological analysis, supporting the differential diagnosis.

Objetivos: O presente estudo propôs critérios histopatológicos para o diagnóstico diferencial entre as entidades patológicas. Materiais e métodos: Cortes histológicos de lesões diagnosticadas microscopicamente como Fibroma Oral (n=61) e Hiperplasia Fibrosa Inflamatória (n=75) foram submetidos a diferentes técnicas de coloração (Hematoxilina-eosina, Tricrômio de Masson e Ácido Fosfomolibidico- Vermelho de Picrosírius) para permitir análises quantitativa e qualitativa. A análise qualitativa da densidade do colágeno foi baseada nas lâminas coradas em Hematoxilina- eosina e observada no centro e periferia de cada lesão. Resultados: Fibras colágenas enoveladas eram mais frequentes e mais densas no Fibroma Oral, enquanto as fibras paralelas e ram observadas na Hiperplasia Fibrosa Inflamatória (teste exato de Fisher, p<0,05). No centro da lesão, fibras colágenas paralelas foram encontradas em 84,6% dos casos de Hiperplasias Fibrosas Inflamatórias e ausentes em 88,88% dos Fibromas Orais. A porção central do Fibroma Oral era caracterizado por um arranjo denso e frouxo das fibras colágenas. Conclusão: o Fibroma Oral e a Hiperplasia Fibrosa Inflamatória possuem características bem distintas que pode ser útil na rotina da análise histopatológica, auxiliando no diagnóstico diferencial.